1. Field of the Invention
The present invention relates to an auxiliary air supply apparatus for an internal combustion engine for motor vehicles or the like, more specifically an intake manifold in the internal combustion engine having a collector section with an improved auxiliary distributor therein.
2. Description of the Prior Art
In an internal combustion engine, when a number of auxiliary apparatus, such as an air conditioner, are put into operation during engine idling, the volume of idling air is inclined to be inadequate. Accordingly, in order to supplement the inadequate volume of air during the engine idling, other means are adapted to supply auxiliary air to the engine.
However, in the internal combustion engine having two intake chambers each communicating with a group of cylinders, e.g. V-type internal combustion engine, the distribution of the auxiliary air to the groups of cylinders is inclined to be uneven. Specifically, as shown in FIGS. 1 and 2, in a conventional V-type combustion engine, multiple units of branched pipes 9 connected to each cylinder are divided into two groups, corresponding to the two groups of cylinders. The internal section of a collector section 4 in an intake manifold 3 which is provided in the downstream side of an intake throttle valve, corresponding to the branched pipes 9 which are divided into two groups, is also divided into chambers 4A and 4B by a partition 11 with a balancing hole 12. An auxiliary air channel 5 bypasses a throttle chamber 1 and throttle valve equipped with an intake duct 2. This auxiliary air channel 5 has an inlet which communicates to the intake duct 2 in the upstream side of the intake throttle valve, and an outlet 10 which communicates to the collector section 4.
Partway into this auxiliary air channel 5, an auxiliary air control solenoid valve 6 is provided for controlling the volume of the flow of auxiliary air in the channel 5 according to the running status of the internal combustion engine and the status of the vehicle. In addition, the collector section 4 and the cylinder of the engine are communicated each other by means of branched pipes 9. A control circuit 7 is adapted to controls either the degree of opening of the auxiliary air control valve 6 or the time that the valve is opened, based on the engine RPM detected by means of a crank angle sensor 8, to maintain a prescribed idling RPM of the engine when the engine is idling. Furthermore, when auxiliary equipment such as air conditioning and power steering devices are running, and when the headlights are used, or, in other words, when the load on the engine is increased the control circuit 7 controls the auxiliary air control valve 6 so as to increase the volume of auxiliary air.
In this type of conventional auxiliary air supply apparatus, the downstream end of the auxiliary air channel 5 takes place at only the auxiliary air feed outlet 10 in the collector section 4 of the intake manifold 3, and the auxiliary air passing through the auxiliary air channel 5 is supplied through the auxiliary air feed outlet 10 in the collector section 4 of the intake manifold 3. For this reason, when a conventional auxiliary air supply apparatus mentioned above is used in an internal combustion engine having two intake chambers, the following type of problems are produced.
The auxiliary air passes through the auxiliary air supply outlet port 10 and first feeds the first chamber 4A, then passes through the balancing hole 12 of the partition 11 and is supplied into the second chamber 4B. For this reason only a small volume of auxiliary air is fed into the second chamber 4B in the collector section 4, as compared to that fed to the first chamber 4A. Therefore, the distribution of the auxiliary air to the cylinders is uneven. This means that the ratio of the mixture and the distribution of the exhaust recycle gas are non-uniform, and that operating conditions and fuel costs, etc., deteriorate.